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User Interface Design Guidance
for RTCA-DO/160
08.30.17
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Agenda
Key Considerations Before Testing
Dynamic Tests
Environmental Tests
EMI / EMC Tests
Summary
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What is RTCA/DO-160?
The Radio Technical Commission for Aeronautics (RTCA) was founded in 1935 and provides standards and guidelines across key aviation policies. The performance standards form the basis of the Federal Aviation Administration regulatory requirements.
– Largely derived from Mil-STD-810 & Mil-STD-461
– Standardized way of defining and simulating conditions on aircraft.
– Initial Release 1975
– Current Revision: RTCA/DO-160 Rev G
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Key Considerations Before Testing
1. Who will be obtaining FAA certification?
2. How will your unit be tested?
a) Standalone Unit vs Next Higher Assembly
3. Sequence of environmental tests.
1. Consideration must be given for units that will be damaged or exhibit residue
2. Perform Dust, Fluids Susceptibility, Salt Fog last
4. How will the unit be powered / operated during testing?
5. What is the PASS / FAIL Criteria?
a) “Determine compliance with applicable equipment performance standards”
Why are these important?
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RTCA/DO-160 Revision G
Dynamic / Environmental
Section 4.0 Altitude
Section 5.0 Temperature Variation
Section 6.0 Humidity
Section 7.0 Shock & Crash Safety
Section 8.0 Vibration
Section 9.0 Explosion Proofness
Section 10.0 Waterproofness
Section 11.0 Fluids Susceptibility
Section 12.0 Sand and Dust
Section 13.0 Fungus Resistance
Section 14.0 Salt Spray
EMI / EMC
Section 20.0 RF Susceptibility
Section 21.0 RF Emissions
Section 25.0 ESD
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Dynamic Tests - Conditions
Section 7.0: Shocks & Crash Safety
– Sustained Acceleration (20g)
– Shock Pulse (11ms or 20ms)
Section 8.0: Vibration
– Sinusoidal Vibration
– Random Vibration
– Sine on Random
Control & Response Accelerometers
– Measure input & transmissibility
Estimate total energy from “area under the curve”
With “g” constant, low frequency requires higher displacement
Section 7.0: Shocks & Crash Safety
Section 8.0: Vibration
Fixed Wing Vibration ≠ Helicopter Vibration
Shaker Table
Helicopter Blade
Frequencies
Centrifuge
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Locking Fasteners
Aerospace Grade
Aluminum
Ruggedized Connector
Dynamic Tests - Design Guidance
Failure Modes
– Ultimate / yield failure
– Fatigue from cyclic vibration
– Sway
– False key actuation
– Loosening fasteners, components
Design Guidance
– Materials selection
– Shock mounts / isolators
– Shift natural frequency (ωo)
– Locking fasteners
– Strain relief
Testing is typically necessary to validate performance
Section 7.0: Shocks & Crash Safety
Section 8.0: Vibration
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Environmental Tests - Altitude
Low pressure ranges from 15,000 ft – 70,000 ft
Overpressure to -15,000 ft
Rapid Decompression from 8,000 ft to max attitude
Can be tested in conjunction with temperature
Failure Modes
– Ballooning of elastomeric members
– Rupturing of sealed areas
Design Guidance
– Modify stiffness of elastomeric members
– Structural reinforcement
– Venting
Section 4.0: Altitude
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Environmental Tests - Temperature & Humidity
Failure Modes
– Condensation
– Thermal expansion
– Material breakdown at temperatureextremes
Design Guidance
– Select materials for Operating and Storage Temps
– Tolerances account for thermal expansion
– Drain ports for condensation
Operating Temps are less severe than Storage Temps
Components &
materials selected
for temperature
extremes
Section 5.0: Temperature Variation
Section 6.0: Humidity
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Environmental Tests - Explosion Proofness
Operating unit cannot ignite fuel-airmixture.
Failure Modes
– Exposed live electrical components
– Arcing
– Excessive heat source
Design Guidance
– Eliminate heat and sparks
– Enclosing live components
– Conformal coating
– Hermetically sealed
Unit must be able to be operated during the test
Conformal coating of
live components
Section 9.0: Explosion Proofness
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Environmental Tests - Waterproofness
Failure Modes
– Gasket or sealing failure
– Circuit failure
– Ingress and pooling
Design Guidance
– Hermetically sealed (exempt from test)
– Gasketing
– Elastomeric boots
– Conformal coatings
– Drain holes
Ingress does not necessarily constitute a test failure
Elastomeric boot
with pressure
sensitive adhesive
Gasket groove
Perimeter seal
Waterproof design for
custom dome switch
Section 10.0: Explosion Waterproofness
Category Y - Condensing Water
Category W - Drip Proof
Category R - Spray Proof
Category S - Continuous Stream
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Environmental Tests - Sand and Dust
Failure Modes
– Gasket or sealing failure
– Circuit failure
– Fouling of moving parts
– Clogging of filters
– Pollution of reservoirs
Design Guidance
– Pressure sensitive adhesive
– Gasketing
– Elastomeric boots
– Conformal coatings
Ingress does not necessarily constitute a test failure
Redesigned
concept with
perimeter sealing
solution
Dust Contamination
on contacts
Pressure Sensitive
Adhesive
Section 11.0: Sand and Dust
Category D - Blowing Dust
Category S - Blowing Sand and Dust
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Environmental Tests - Salt Spray
Failure Modes
– Corrosion
– Material breakdown
Design Guidance
– Material selection
– Plating & processing
– Properly sealed unit
– Conformal coatings
Salt Fog Chamber
Gold Plated
Components
Pressure Sensitive
Adhesive
Section 14.0: Salt Spray
Category S - Normal aircraft operations
Category T - Severe with direct exposure
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Environmental Tests - Fungus
Material coupon testing.
Failure Modes
– Material promotes fungus growth
Design Guidance
– Qualification through previous testing
– Material selection
Section 11.0: Fungus Resistance
Category F - Severe fungus exposure
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Environmental Tests - Fluids
7 General Fluid ClassesFuels Hydraulic Fluids
Lubricating Oils Solvents / Cleaners
De-Icing Fluid Insecticides
Sullage Disinfectant
Dielectric Fluid Fire Extinguishants
Failure Modes
– Material Degradation
Design Guidance
– Material & finish selection
– Conformal coating
Section 13.0: Fluids Susceptibility
Category F - 7 General Fluid Classes
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EMI / EMC Test Conditions
Section 20: RF Susceptibility
– Conducted 10 kHz – 400 MHz
– Radiated 100 MHz – 18 GHz
– Sect 20.5 Radiated Susceptibility is directional
• Anechoic chamber
– Sect 20.6 Radiated Susceptibility is 360°
• Reverberation chamber
Section 21: RF Emissions
– Equipment does not emit undesired RF noise
– Scan of the entire frequency range applicable
Section 25: ESD
– Human contact induced ESD event
– Directed at specific human contact locations
– Must withstand multiple 15KV discharges
Reverberation Test Method for Radiated Susceptibility is Worst Case
Measurements from 14 kHz to 1 GHz
EMI Chamber Test Setup
Section 20: RF Susceptibility
Section 21: RF Emissions
Section 25: ESD
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EMI / EMC Tests - Design Guidance
Failure Modes
– Loss of function
– Undesired performance
– Excessive emissions
Design Guidance
– Shielding layers
– Passive components (diodes, chokes)
– Effective bonding & grounding
– Conductive elastomers
– Conductive coatings
Shielding effectiveness testing can help predict RF behavior
Grounding terminal
Shielding layer
Conductive Chem Film per
Mil-DTL-5541 Class 3
Shielding layer
Overbraid shielding
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Summary
RTCA-DO/160 is one of the last hurdles in obtaining airworthiness certification.
A comprehensive understanding of the test conditions and requirements helps obtain certification.
A design fix for one test may cause a failure on another in the system.
Development Testing BEFORE formal DO-160 qualification is recommended.
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Q&A
Questions?
– Enter any questions you may have in the Control Panel
– If we don’t have time to get to it, wewill reply via email
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